In 2002 we reported the occurence of avascular necrosis of bone (usually the hip) in 15 asymptomatic patients with HIV disease. We are currently assessing the natural history of avascular necrosis in the asymptomatic additional ten patients with symptomatic disease. The occurence of pain and functional disability is being assessed. The development of AVN at other sites is also being evaluated by yearly MRIs. The study will elucidate natural history and risk factors for this unexpected complication of treated HIV disease. This follow-up continues. A formal evaluation is ongoing in order to determine natural history of this disorders. This is one of the largest such cohorts being followed. This type of long term follow up is necessary in order to determine the natural history and clinical relevance of findings.